NST 103 - LEC 1-3

Question 1

(1) GI tract - order of travel + accessory organs

Answer 1

mouth (salivary glands) > esophagus > stomach > small intestine (liver, gallbladder, pancreas) > large intestine > anus

Question 2

(1) GI tract functions

Answer 2

• digestion: (chemical, physical) reduce molecule size & repackage to facilitate absorption
• absorption: movement from GI tract to lymph ot blood
• secretion: movement into lumen of GI tract
• mobility: muscles mix & move via peristalsis
• storage + elimination
• barrier: between external & internal environments

Question 3

(1) GI tract layers

Answer 3

*order from inner to outer

1. mucosa (inside, towards lumen)
2. submucosa (next to mucosa)
3. muscularis (circular + longitudinal)
4. adventitia (esophagus) or serosa (stomach, intestine)

Question 4

(1) GI tract tissue types

Answer 4

• epithelia : various cell types for secretion
• connective: supportive structure for tissues, storage, transport, signaling
• blood: absorption + transport of compounds & cells
• lymphatic: transports lipids, interstitial fluid; facilitates immune function
• muscle: smooth & striated to process, mix, and move food along GI tract
• nerve: neural & glial cells grouped into plexuses to coordinate various gut functions

Question 5

oral cavity + salivary glands functions

Answer 5

• chewing, initiating digestion, swallowing
• goal: form bolus

Question 6

salivary glands anatomy

Answer 6

• parotid gland: largest, further back by ear area (lymph nodes present here)
• sublingual gland: directly below tongue
• submandibular gland: below sublingual gland (& bigger)

Question 7

saliva functions
(500ml/day produced)

Answer 7

• moistens food
• glycoproteins (mucin) lubricate
• salivary amylase initiates digestion of starch
• antimicrobial agents reduce infection risk
• acts as PH buffer (protein, phosphate, bicarbonate)

Question 8

stomach functions

Answer 8

• goal: form chyme (food + secretions)
• accept bolus from lower esophageal sphincter
• sense presence of food (stretching, mechanoreceptors)
• mix: via weak peristaltic waves in upper stomach
• digest: secretion of acid, pepsinogen, gastric lipase

-empty: antral peristalsis (induced by gastrin, blocked by CCK)

• additional: store food; ill bacteria; some absorption/metabolism of ethanol; absorption of drugs & small water soluble compounds